Browsing by Author "Cunha, Maria Emilia"
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- Improvement of the cryopreservation protocols for the dusky grouper, Epinephelus marginatusPublication . F Riesco, Marta; Raposo de Magalhães, Cláudia; Engrola, Sofia; Martinez-Paramo, Sonia; Mira, Sara; Cunha, Maria Emilia; Cabrita, ElsaThe dusky grouper, Epinephelus marginatus, is a potential species for aquaculture production although the limited number of males kept in captivity has been the cause of some constraints in its production. Sperm cryopreservation emerged as a solution for this problem. However, spermatozoa can be severely affected by freezing/thawing processes and poor sperm quality is a limiting factor in reproduction success. The present study aimed at evaluating two main aspects in the design of a cryopreservation protocol-extender additives (taurine, glucose, cholesterol, BSA) and sperm containers (0.5 mL straws, 2 mL cryovials and 5 mL macrotubes). Sperm quality was assessed through the evaluation of the percentage of motile cells, viable cells, DNA fragmentation, lipid peroxidation and apoptosis. Some specific techniques, such as Caspase 3/7 detection, which provides information on membrane integrity and cell death, detecting early and late apoptotic and necrotic events, were required to establish an optimized cryopreservation protocol for this species. Taurine was the most suitable cryopreservation additive in terms of viable cells and cholesterol presented the highest percentage of necrotic cells in this study. Caspase 3/7 assay enabled us to detect necrotic damage induced by cryopreservation. Statement of relevance: The development of reproductive tools in dusky grouper, a potential species for aquaculture production, emerges as important tool to decrease the number of wild males maintained in captivity. A cryopreservation protocol was previously described for this species although several constraints in terms of sperm quality were detected. Our work provided new evidences that cryopreservation protocols can be improved through the addition of certain additives and use of appropriate sperm containers. Specific sperm analysis was crucial to identify and establish the most suitable conditions for breeders management and species conservation purposes. (C) 2016 Elsevier B.V. All rights reserved.
- Seagrass meadows improve inflowing water quality in aquaculture pondsPublication . de los Santos, Carmen B.; Olivé, Irene; Moreira, Márcio; Silva, André; Freitas, Cátia; Araújo Luna, Ravi; Quental-Ferreira, Hugo; Martins, Márcio; Costa, Monya; Silva, João; Cunha, Maria Emilia; Soares, Florbela; Pousão-Ferreira, Pedro; Santos, RuiWater quality is critical for fish health in aquaculture production. In flow-through systems, the inflowing water normally requires quality controls and treatments for being supplied from coastal water bodies that can be polluted by nutrients, suspended solids, and microorganisms. Here we assess how seagrass meadows benefit aquaculture systems through the provision of ecosystem services (water filtration, biological control, and regulation of dissolved gasses) in the water reservoir that supplies earthen ponds in an aquaculture system in southern Portugal. In the 1.45-ha reservoir, seagrasses retained daily an estimate of 0.8–1.8 kg d−1 of nitrogen, 0.04–0.07 kg d−1 of phosphorus in their biomass, and 0.7–1.1 kg dw d−1 of suspended total particulate matter, bringing benefits in terms of nutrient and particle removal from the water column. Diel and spatial variation in faecal coliforms levels (Escherichia coli) in the reservoir suggested that seagrasses, in combination with light exposure, may reduce the levels of this pathogen. Furthermore, the seagrass-dominated system oxygenated the water through photosynthesis at a faster rate than the respiratory oxygen consumption, maintaining the system above the aquaculture minimum oxygen. This study demonstrates that seagrasses can be used as a nature-based solution to overcome water quality challenges in flow-through aquaculture ponds.
- Tracking 130 years of coastal wetland reclamation in Ria Formosa, Portugal: Opportunities for conservation and aquaculturePublication . Mendes Da Silva De Sousa, Carlos A; Cunha, Maria Emilia; Ribeiro, LauraEconomic activities in coastal wetlands are often perceived as incompatible with nature conservation. This negative perception stems from the visible impacts resulting from a continuous process of coastal wetland reclamation, as human pressure increases significantly in global coastal areas. The largest coastal wetland area in southern Portugal, the Ria Formosa, shares a similar perception, where current nature protection status often conflicts with the needed economic development. Here we explore how the economic activities influenced the wetland reclamation process in Ria Formosa, addressing namely aquaculture identified as an activity with a significant compatibilization potential. Different datasets were merged in a Geographical Information System, tracking land use change in Ria Formosa wetlands over the last 130 years at decadal intervals. Our results show that since the end of the 19th century nearly 2000 ha of wetlands were converted to anthropic environments, resulting in a 20 % natural area reduction. From 1885 until the mid-20th century, land use policy was influenced by the significant regional seafood preservation industry, with large swaths of wetlands diked, drained and excavated to give place to traditional salt farms. The following economic downturn gave place for the late industrialization of salt farms, further increasing the reclaimed wetland areas, later stalling with the recognition of the environmental importance of Ria Formosa in 1978. Aquaculture only gained momentum in 1980's with the support of European funding, resulting in the conversion of many unproductive diked areas. However, late 20th century and current land use policy shifted to a nature conservation focus, therefore limiting the use of previously reclaimed areas, a challenge that influenced the abandonment of the modified areas. By studying the long-term change of land use in Ria Formosa, we argue that in high conservation value areas new policies should be considered that stimulate the development of an ecosystem approach to economic activities, namely aquaculture, improving simultaneously the regional environmental status and socioeconomic sustainable development.